If you do the milk/seeds thing, then let them rise upside down, any deflation seems to work itself out in the final rise. Similarly, any deflation from when you flip them over again for baking seems to be taken care of by oven spring. I find putting the seeds on before the final rise helps them stick. (I find a little diluted honey helps stick them even better, I've used a honey-and-milk mixture a few times, too.)
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